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, E. SCHUBERT.

y y SPRING BACK PoR BOOKS. No.Y 402,485. Patented Apr. 30, 1889.f

`IIIIIIIHIIIIII""Ill" UNITED STATES PATENT OFFICE.

FRITZ E. SCHUBERT, OF ZURICH, SWITZERLAND, ASSIGNOR TO CARL FREIDRICK SCHUBERT, OF SAME PLACE.V

SPRING-BACK FOR BOOKS.`

SPECIFICATION forming part of Letters Patent No. 402,485, dated April 30, 1889.

Application led December 26, 1888. Serial No. 294.632. (No model.)

To @ZZ whom It may concern:

Be it known that I, FRITZ E. SCHUBERT, a

citizen of Switzerland, residing at Zurich, Switzerland, have invented a new and useful Improvement in Spring Backs for Books, whereof the following is a specication. t My invention relates to spring backs for books, especially of. account-books and the like; and its object is to impart to the said backs a higher and more permanent degree of resilience than is attainable by materials in use for this purpose at present.

I-Ieretofore the inner portion of spring-backs has ordinarily been made by gluing together several layers of thin pasteboard. Springbacks thus prepared are, however, too stiff at y the beginning, so that the books provided therewith can only be opened with difficulty and not without straining them, while after some time of use the backs become slack, and then do not any more answer their purpose to keep the leaves of the opened book flat. Metallic fittings combined with such backs either increase their stiness or they soon become useless by rusting or bending out of shape or breaking. In View of obviating these defects I make the spring-backs with a core or inner layer consisting in apiece of hide so prepared', without tanning, as to present the required degree of resilience, and formed previous to its application in an arc of a circle corresponding to the shape of the back, but preferably of somewhat smaller radius than the back is to have when the book is closed. The method of preparing the said cores is partly analogous to the ordinary method of treating hides for tanning. It consists in slackening a rawhide in lime,in unhairing and Washing it, in beating or rolling the same, so as to make its Vthickness uniform, and in steeping it in an infusion of birds dung, (preferably pigeon-dung.) After an'- other cleansing operation, pieces of the required size are cut from the hide, stretched in wet state on cylindrical molds, and allowed to dry. Spring-back cores are thus obtained which possess that lasting and unvarying resiliency which has ever been a desideratum in book-binding. They are light in comparison to their power of returning to their original form when bent out of the same. They are cheap, and by their employment the binding of books is facilitated. p

In the annexed drawings, Figure l shows in transverse section an account-book having its back provided with the described core. Fig. 2 is a perspective view of the book without spring-back and outer portion of cover. Fig. 3 is a like view of the new core ready for application and Fig. 4, a like view of the finished book in open state, showing how the resilient back operates to make the leaves lie flat. Figs. 5, 6, and 7 are sections representing the manner in which the core allowsv the springback to yield when the book is being opened and causes the back to assume the original form of the core when the book is entirely open.

In Fig. 1, c is the core, a2 its coveringof leather, cloth, or the like, anda3 the lining.

d, Figs. l and 2, are the leaves of the book, stitched to the flexible strips e, which are glued to the pieces of pasteboard, b, forming the inner layers of the two covers.

c are the outer layers of the cover, attached by the lining a3 and the covering a2 to the spring-back and glued to the inner layers, b.

I claim as my invention.

l. A spring-back for books, having an in-` ner layer or core consisting in a resilient piece of untanned hide formed in an arc of a circle, substantially as described.

2. An article of manufacture consisting in a resilient piece of untanned hide formed in an arc of a circle and adapted to be used as a core for the spring-back of a book, substantially as set forth.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

FRITZ E. SCHUBERT.

Witnesses:

EMIL SCHMID, RUDOLF TOBLER. 

